One duct detector structure has been disclosed in U.S. Pat. No. 6,124,795 entitled “Detector Interconnect System”, issued Sep. 26, 2000. The '795 patent is assigned to the Assignee hereof and is incorporated herein by reference.
Many of the known duct smoke detectors incorporate a smoke sensor and a power supply board which incorporates power supply circuitry and alarm indicating relays. In such smoke detectors, the smoke sensor unit makes an alarm determination. The circuitry on the power board then receives a signal from the smoke sensor indicating an alarm condition and responds thereto by activating local alarm indicating relays, and/or light emitting diodes to indicate an alarm condition. Such power boards are unable to make decisions based on multiple detected conditions where the unit incorporates more than one smoke sensor. This results in the sensor having to contain the filtering and processing algorithms. Thus, multiple sensors requires multiple algorithm processing capability. Further, such power boards are unable to signal the condition of the respective sensors to a displaced display/input unit in the absence of extra conductors.
There is thus a continuing need for duct detectors which can more effectively support multiple local sensors and signal remote indicating or accessory devices than have heretofore been available. Complex processing can thus be handled by one device rather than at each individual sensor, therefore simplifying the design. Preferably such duct detectors could be flexible enough to incorporate a plurality of sensing units and be able to communicate with remote indicators or accessory units, either via cables or wirelessly, without substantial additional expense or manufacturing complexity.